Tolong bantu 2 soal luas segitiga dong
aplikasi trigonometri
1.
∆ABC
AC = 6 cm
∠A = 120°
∠B = 30
∠C = 180° – (A + B) = 30°
∠B = ∠C = 30°
Maka :
AC = AB = 6 cm
Luas ABC
= 1/2 × AB × AC × sin A
= 1/2 × 6 × 6 × 1/2 √3
= 9√3 cm² ✔
2.
∆ABC
AB = 17 cm
BC = 19 cm
AC = 8 cm
rumus Heron
S = (a + b + c)/2
S = (17 + 19 + 8)/2 = 22
Luas ABC
= √(S(S – a)(S – b)(S – c))
= √(22(22 – 19)(22 – 8)(22 – 17))
= √(22 . 3 . 4 . 5)
= 2√330 cm²
= 36,33 cm² ✔